Method of centrifugal casting



A. K. HIGGINS METHOD OF CENTRIFUGAL CASTING Oct. 5, 1948.

Patented Oct. 5, 1948 mz'rnon or canramrcar. CASTING Arthur K. Higgins, Waukesha, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis. a corporation of Delaware Application June 10, 1944, Serial No. 539,636

This invention relates to centrifugal and centrifuged castings and has for its object the provision of an improved method for producing such castings in a manner affording one or more of the following advantages: (1) minimizing loss of heat in the transfer of the molten'metal from the melting container to the mold; (2) reducing to a minimum or entirely eliminating the. formation of dross on the metal as it is transferred from the melting container to the mold and also on the metal contained in the mold cavity; (3) the introduction of molten metal into the mold cavity with a minimum of turbulence and agitation; (4) eliminates the necessity of weighing or otherwise measuring the molten metal prior to its introduction into the mold; (5) eliminates the handling and the resulting spillage heretofore usually experienced in transferring the molten metal from the melting container to the' mold; and (6) the production of cleaner and more accurately dimensioned castings.

The procedure necessary for attaining one or 8 Claims. (01. 22-2005) more of the advantages hereinabove mentioned will become readily apparent as the disclosure progresses and particularly points out additional features considered of special importance and of general application with respect to rotating mold structures although illustrated and described in connection with a mold designed for the centrifugal casting of brass bushings.

Moreover, although it may be apparent that the invention is particularly applicable for casting metals and alloys having high melting points, such for example as copper, brass and steel, into articles of annular shape, it is in no manner so limited and may accordingly be considered as consisting ofthe various methods and of the apparatus including details of construction, correlations of elements, and arrangements ofparts as is more fully set forth in the appended claims and in the detailed description, reference being had to the accompanying drawing, in which:

Fig. 1 illustrates a casting machine embodying the invention;

Fig. 2 is an enlarged section taken on line II--II of Fig. 1;

Fig. 3 is a view similar to Fig. 2 illustrating a modified mold structure; and

Fig. 4 is another view similar to Fig. 2 illustrating still another modified mold structure.

Referring to Fig. 1, it is seen that the invention may be practiced with the aid of apparatus comprising a rigid supporting structure i presenting a pair of spaced vertically extending, parallel guide rails 2, a motor 3 having a rotatable shaft z 4 and projections 6 guidingly engaged with the rails '2, a counter balanced mechanism including pulleys i and 8 mounted on the structure i and a cable 9 passing over the pulleys I and 8 and having one end attached to the casing of motor 8 and its other end secured to a weight I I, a mold l2 detachably connected in coaxial relation to the lower end of shaft 4 for movement therewith,

and a molten metal container l3 disposed beneath and in coaxial relation with respect to shaft 4 and mold i2.

The mold l2 (see Fig. 2) is provided with a coaxially depending cylindrical spout portion l4 to the container i3 for the purpose of selectively dipping the lower end of spout i4 into the body of molten metal confined in container l3. Mold I2 preferably consists of a main body element or portion i6 and a cover element or portion H detachably connected in cavity forming relation in any suitable manner such as by means of stud bolts i8. Spout I4 is illustrated as being integral with cover element l1 and in coaxial communicating relation with respect to the bottom portion of a bushing-forming mold cavity l9 which is in turn disposed in coaxial relation with respect to shaft 4. Body element i6 is preferably provided with a vent passage 2i communicating with the top central portion of mold cavity IS. The lower end of shaft 4 is externally threaded and the body portion iii of the mold is provided with a coaxial, internally threaded hollow boss 22 by means of which the mold can be readily secured to and removed from the shaft 4 such a connection preferably including a lock nut 23 on thethreaded portion of shaft 4.

In practicing the invention with apparatus of cavity i9 solidifies whereupon the motor may be stopped, the main and cover elements of the mold separated to remove the casting (if desired, the mold may be first removed from shaft 4 and another mold put in its place to speed production),

The introduction of molten metal into the mold cavity in the manner just described is accomplished by dipping the end of the spout into the molten metal a distance sufiicient for molten metal to be forced into the lower end of the spout by hydrostatic pressure and by rotating the mold at a speed such that the rotating body of confined metal (the metal confined within the lower I end of the spout is caused to rotate by frictional contact with the confining wall surface) acquires a centrifugal force or pressure acting at right angles to the longitudinal axis of the spout which is sufilcient to cause a thin layer of molten metal to ascend the wall of thespout and enter the mold cavity; the molten metal continuing to flow up the spout and into the mold cavity until the cavit is filled as indicated in Fig. 2, whereupon the ascension of molten metal ceases unless the speed of rotation is increased. The mold may be rotating at the desired speed when the spout is dipped into the molten metal or its rotation may be initiated after the spout has been so dipped.

metal entering the lower end of the spout to move upward therethrough and into the mold cavity. Moreover, it is also entirely immaterial whether the interior of spout II has a smooth cylindrical surface 24 as shown in Fig. z'or a surface of a different nature andshape adapted to assist the movement of molten metal upward thereover. For example, the spout may have a smooth sur-' face 26 of inverted frusto-co'nical shape as is clearly shown in Fig. 3 in which like numerals are used to designate the same or corresponding parts. with a spout of this shape, the flow of molten metal upward through the spout is greatly increased thereby permitting the mold cavity to either be filled more rapidly for a given speed of mold rotation or in the same time with a lesser speed of rotation. In addition, this shape of spout affords an additional advantage in that it facilitates the removal of the thin layer of solidifled metal remaining in the spout.

Fig. 4 shows a mold having a spout similar to that shown in Fig. 3 and a plurality of separate similar cavities 21 symmetrically arranged with respect to the spout and a corresponding number of gates 28 placing the upper portions of the cavities 21 in communication with the upper interior portion of the spout; the gates being preferably inclined upward toward the spout to facilitate venting of the cavities. This mold is similar in all other respects tothose shown in Figs. 2 and 3 and consequently like numbers have been used to designate the same or corresponding parts. The invention may be practiced with this type of mold in exactly the same manner as herein set forth with respect to Figs. 1 and 2 and therefore a further description in this connection is deemed unnecessary for a complete understanding of the invention.

The invention is of general application with respect to the production of centrifugal and centrifuged castings of various shapes and may be practiced with apparatus other and different from that herein shown and described for purposes of illustration. And it should therefore be understood that it is not intended to limit the invention to details of the methods herein disclosed as various modifications within the scope of the appended claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

1. A method of introducing molten metal into a mold having a spout projecting therefrom and communicating with an interior cavity which comprises providing a body of molten metal, establishing a superposed relation of the mold relative to the body of molten metal with the lower end of the spout extending beneath the surface of said metal, and causing the molten metal entering the lower end of said spout to rotate therein with suflicient speed to move upward therethrough and into the mold cavity substantially entirely through the effect of said rotation of the molten metal and in sufiicient quantity to fill the cavity to the extent required to form the article to be molded.

2. A method of introducing molten metal into a mold having a spout projecting therefrom and communicating with an interior cavity which comprises providing a body of molten metal, establishing a superposed relation of the mold relative to the body of molten metal with the lower end of the spout extending beneath the surface of said metal, and effecting a relative rotation of the body of molten metal and mold sufficient to cause molten metal entering the lower end of said spout to move upward therethrough and into the mold cavity substantially entirely through the efiect of said relative rotation of the molten metal and mold and in suiTicient quantity to fill the cavity to the extent required to form the article to be molded.

3. A method of introducing molten metal into a mold having a spout projecting therefrom and communicating with an interior cavity which comprises providing a body of molten metal, establishing a superposed relation of the mold relative to the body of molten metal with the lower end of the spout extending beneath the surface of said metal, and rotating the mold at a speed sufiicient to cause molten metal entering the lower end of said spout to move upward therethrough and into the mold cavity in suflicient quantity to fill the cavity to the extent required to form the article to be molded and substantially entirely through the efiect of said rotation of the mold.

4. A method of casting comprising providing a mold having a spout projecting therefrom and communicating with the interior of the mold, providing a body of molten metal, establishing a superposed relation of the mold relative to the body of molten metal with the lower end of the spout extending into the metal, rotating the mold at a speed sufficient to cause molten metal entering the lower end of said spout to move upward therethrough and 'into the mold cavity in sufiioient quantity to fill the cavity to the extent required to form the article to be molded and substantially entirely through the effect of said 5 mold having a spout projecting therefrom and communicating with an interior mold cavity, providing a body of molten metal. establishing a superposed relation of the mold relative to the body of molten metal with the lower end of the spout extending beneath the surface 01 said metal, rotating the mold at a speed and for a time sumcient to cause molten metal entering the,-

lower end of said spout to move upwardtherethrough and ill] said cavity to the extent required to iorm the article to be molded and substantially entirely through the eiiect oi said rotation of the mold, and separating the mold and body oi molten metal while continuing rotation of the mold until the metal confined in said cavity has solidified. 4

6. A method 01' casting comprising providing a mold having an annular cavity and a filling spout therefor projecting from said mold in coaxial relation with respect to said cavity. providing a body of molten metal, establishing a superposed relation of the mold relative to the body 0! molten metal with the lower end oi the spout extending beneath the surface of said metal. rotating the mar a mold about an aids-coincident with the axis of I ARTHUR K. mnms.

aaraaauoas'cnnn .The iollowing reierences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 898,037 Underwood July 14, 1906 1,526,303 Rockwell Mar. 3. 1925 1,636,228 Gray ---July-19, 1927 r 2,042,015 Moormann May 264936 2,262,501 1 Bull! May 12. 1942 

